BULKING OF SAND

The increase in volume of a given mass of fine aggregate caused by the presence of water is known as bulking.

Free moisture forms a film of water around each particle. The bulking of fine aggregate is caused by these films of water which pushes the particles apart. Therefore, no point of contact is possible between the particles. This causes increase in volume of the mass of fine aggregate. The extent of bulking depends upon the percentage of moisture present in the sand and the fineness of sand particles.

Figure 1 shows the effect of moisture content on bulking. It is seen that bulking increases with the increase in moisture content up to a certain limit and beyond that the further increase in the moisture content results in the decrease in the volume. This is due to the fact that after addition of certain amount of water in the fine aggregates, the further addition of water breaks the film around the particles and hence, volume gradually decreases.

Figure 1. Effect of moisture content on the bulking of sand

For ordinary sands the bulking usually varies between 15 to 30 percent. Fine sands bulk more and the maximum bulking is obtained at a higher water content that the coarse sand. In extremely fine sand, the bulking may be as much as about 40 percent at a moisture content of 10 percent but such sand is unsuitable for concrete. In case of coarse sand, the increase in volume is negligible due to the presence of free water as the thickness of the moisture film is very small compared with the size of the particle.

The percentage of bulking is to be determined as per IS: 2386-1963 (Part III). Put sufficient quantity of the sand loosely into a container until it is about two-thirds full. Level off the top of the sand and pushing a steel rule vertically down through the sand at the middle to the bottom, measure the height. Suppose this is h cm.

Empty the sand out of the container into another container where none of it will be lost. Half fill the first container with water. Put back about half the sand and rod it with a steel rod, about 6 mm in diameter, so that its volume is reduced to a minimum. Then add the remainder of the sand and rod it in the same way. Smooth and level the top surface of the inundated sand and measure its depth at the middle with the steel rule. Suppose this is h₁ cm.

The percentage of bulking of the sand due to moisture shall be calculated from the formula: 

REGULATORY REQUIREMENTS OF WASTE MANAGEMENT

Solid waste policy in the US is aimed at developing and implementing proper mechanisms to effectively manage solid waste. In the US, the Environmental Protection Act (EPA) regulates household, industrial, manufacturing and commercial solid and hazardous wastes under the 1976 Resource Conservation and Recovery Act (RCRA). The RCRA is the principal federal law in the US governing the disposal of solid waste and hazardous waste. The US Congress enacted RCRA to address the increasing problems the nation faced from its growing volume of municipal and industrial waste. RCRA amended the Solid Waste Disposal Act of 1965. It sets national goals for:

• Protecting human health and the natural environment from the potential hazards of waste disposal. 
• Energy conservation and natural resources. 
• Reducing the amount of waste generated, through source reduction and recycling. 
• Ensuring the management of waste in an environmentally sound manner.

The Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), also known as “Superfund” was enacted in 1980 to address the problem of remediating abandoned hazardous water sites, by establishing legal liability, as well as trust fund for clean up activities.

In general, CERCLA applies to contaminated sites, while RCRA’s focus is on controlling the ongoing generation and management of particular waste streams. In 1984, the US Congress expanded the scope of RCRA with the enactment of Hazardous and Solid Water Amendments (HSWA). The amendments strengthened the law by covering small quantity generators of hazardous waste and establishing requirements for hazardous waste incinerators and the closing of substandard landfills. In 1986, SARA (Superfund Amendments and Reauthorization Act of 1986) addressed clean up of leaked underground storage tanks and other leaking waste storage facilities. The amendments established a trust fund to pay for the clean up of leaking underground storage tank sites where responsible parties cannot be identified.

In India, waste management is governed by Ministry of Environment, Forest and Climate Change (MoEF) who work together with State Pollution Control Board set up in various states.

Certain laws are also present in the legal set up which helps in regulation of waste in India. The National Environment Policy, 2006 laid emphasis not only on disposal of waste but also recycling and treating waste. Some of the laws for the purpose of waste regulation are stated as under:

THE ENVIRONMENT PROTECTION ACT (EPA)

This act was enacted in 1986 by the Parliament of India and it aims to establish a sufficient protection system. This act confers powers to the Central Government to regulate all forms of waste. It is one of the primary legislatures to protect the environment and regulation of waste.

BIO-MEDICAL WASTE RULES, 1998

The aim of these rules is to ensure that bio-medical wastes are safely disposed of. Biomedical wastes can be defined as any waste or by-product generated during treatment, immunization and treatment of human beings or animals or in research activities. The BMW rules apply to various institutions like nursing homes, animal dispensaries, veterinary homes, blood banks, dispensaries, pathological laboratories, etc. The BMW rules prohibit mixing of biological wastes with any other types of wastes. The general rule provided is that biomedical wastes cannot be kept stored beyond a period of 48 hours without being treated. Further, all institutions covered under the rules are to mandatorily set up treatment facilities like microwave system, autoclave etc.

THE BATTERIES RULES, 2001

The Batteries Rules were notified to set up a mechanism in place which dealt with the disposal of lead acid batteries.  The Rules apply to every manufacturer, recycler, dealer, importer, assembler, bulk consumer and consumer. The Rule makes it compulsory for every consumer to deposit the used batteries back with the dealer, manufacturer, recycler or labelled collection centres. If a recycler wants to import used batteries in India, for the purpose of recycling, he must obtain custom clearance. Additionally, import of batteries will be allowed only upon producing valid registration with Reserve Bank of India and MoEF and providing an undertaking in prescribed format along with a copy of the latest half-yearly return.

THE HAZARDOUS WASTES RULES, 2008

Management of hazardous waste is a very complex issue. The Rule places an obligation on the occupier of hazardous waste to safe and sound handling of environmental waste. The occupier is that person under whose charge there is a plant or unit or factory which produces hazardous wastes as a result of their operation. The occupier must sell or send the hazardous waste to a re-processor or recycler, who is authorized by the government to dispose of the waste in a safe manner. Any person who is engaged in storage, package, collection, destruction, conversion, processing, etc., also has to take authorization from the State Pollution Board. Sale or transfer of hazardous waste can be done only after obtaining a valid registration from Central Pollution Board (CPCB).

THE PLASTIC WASTE RULES, 2011

The PWM Rules are set up to control the use, manufacture and recycling of plastic waste. The Rule has uniform applicability towards all distributors, users, retailers, and manufacturers of plastic products. The Rule makes it compulsory for every manufacturer of plastic products and recycler to obtain registration from State Pollution Control Board. The Rule also states that no retailer can provide plastic bags free of cost. This is done to ensure that people use plastic bags judicially.

THE E-WASTE RULES, 2011

The primary aim of the EWM is to put in place a system which manages e-waste in an environment-friendly way by regulating the issue of recycling and disposal of e-waste. E-waste is a problematic issue in India. With the growing economy and the technological advancement, India is becoming a hub for the IT sector. This creates a lot of e-wastes, disposal of which is necessary. The Rule empower the concerned state agencies to control, supervise and regulate relevant activities connected with e-wastes management such as collection, segregation, dismantling and recycling.

PILE LOAD TEST

The most reliable method for determining the load carrying capacity of a pile is the pile load test. The set-up generally consists of two anchor piles provided with an anchor girder or a reaction girder at their top (Figure 1). The test pile is installed between the anchor piles in the manner in which the foundation piles are to be installed. The test pile should be at least 3B or 2.5 m clear from the anchor piles.

Figure 1. Pile Load Test

The load is applied through a hydraulic jack resting on the reaction girder. The measurements of pile movement are taken with respect to a fixed reference mark. The test is conducted after a rest period of 3 days after the installation in sandy soils and a period of one month in silts and soft clays. The load is applied in equal increment of about 20% of the allowable load. Settlements should be recorded with three dial gauges. Each stage of the loading is maintained till the rate of movement of the pile top is not more than 0.1 mm per hour in sandy soils and 0.02 mm per hour in case of clayey soils or a maximum of 2 hours (IS: 2911-1979). Under each load increment, settlements are observed at 0.5, 1, 2, 4, 8 12, 16, 20, 60 minutes. The loading should be continued upto twice the safe load or the load at which the total settlements reaches a specified value. The load is removed in the same decrements at 1-hour interval and the final rebound is recorded 24 hours after the entire load has been removed.

Figure 2 shows a typical load-settlement curve (firm line) for loading as well as unloading obtained from a pile load test. For any given load, the net pile settlement (S_n) is given by

S_n = S_t – S_e

Where S_t = total settlement (gross settlement); S_e = elastic settlement (rebound)

Figure 2 also shows the net settlement (chain dotted line).

Figure 2. Load Settlement Curve

Figure 3 shows two load-net settlement curves obtained from pile load tests on two different soils. At the ultimate load (Q_u), the load-net settlement curve becomes either linear as curve (2) or there is a sharp break as in the curve (1), as shown in the figure. The safe load is usually taken as one-half of the ultimate load.

According to IS: 2911, the safe load is taken as one-half of the load at which the total settlement is equal to 10 percent of the pile diameter (7.5 percent in case of under-reamed piles) or two-thirds of the final load at which the load settlement is 12 mm, whichever is less. According to another criterion, the safe load is taken as one-half to two-thirds of the load which gives a net settlement of 6 mm.

The limiting settlement criteria are also sometimes specified. Under the load twice the safe load, the net settlement should not be more than 20 mm or the gross settlement should not be more than 25 mm. 

SOIL NAILING

Soil Nailing is a construction technique used to reinforce soil to make it more stable. Soil nailing is used for slopes, excavations, retaining walls etc. to make it more stable. In this technique, soil is reinforced with slender elements such as reinforcing bars which are called as nails. These reinforcing bars are installed into pre-drilled holes and then grouted. Soil nailing is used to stabilize the slopes or excavations where required slopes for excavation cannot be provided due to space constraints and construction of retaining wall is not feasible. It is just an alternate to retaining wall structures. As the excavation proceeds, shotcreting or other grouting materials are applied on the excavation face to grout the reinforcing steel or nails. These provide stability to the steep soil slope. Soil nailing technique is used for slopes or excavations alongside highways, railway lines etc.

Principle theory of Soil Nailing:

According to Abramson (2002), the soil mass behind the soil slope is divided into an active zone and a passive zone which are separated by a shear face called slip surface. The stabilizing manner depends on the soil frictional force between the soil nail surface and soil which is generated by the surrounding soil mass in passive zone. The soil nail must penetrate beyond the slip surface into the passive zone.

Applications of Soil Nailing:

Soil Nailing has been used for both temporary and permanent works. The main applications of soil nailing are summarized as under: 

1. It can also be used for natural hillsides stabilization and disturbed terrain. 
2. Roadway cut excavations. 
3. It can be used to stabilize the man made soil cut slopes. 
4. Road widening under an existing bridge end. 
5. Repair and reconstruction of existing retaining structures. 
6. Providing an earth retention system for deep excavations. 
7. Supporting and strengthening ground around tunnel excavations.

Advantages of Soil Nailing: 

1. Soil Nailing results in saving in cost when compared to other methods/ cost effective technique. The equipments required for execution of soil nailing are relatively small scale, easily movable and produce little noise/ simple and equipments. 
2. Soil nail installation is relatively rapid and uses typically less construction materials. 
3. The maximum lateral displacement of the soil nailed cut at the time of excavation was generally not more than 0.3 % of excavation depth. 
4. Soil Nailing provides an obstruction free working environment. The technique also requires lesser working space for the construction of soil nail wall. 
5. Soil Nailing performs well even in seismically active regions/ suitability during earthquakes. 
6. Soil nail walls are relatively flexible and can accommodate relatively large total and differential settlements.
7. Shotcrete facing is typically less costly than the structural facing required for other wall systems.

Limitations of Soil Nailing:

1. Unsuitable soil: Cohesionless soil slopes are not suitable for soil nails for increasing slope stability. This is because during the drilling of the hole, the un-grouted hole may collapse. Usually, casing drilling may be applied during the drilling process. 
2. Groundwater: Soil nailing has to occur above groundwater level. When soil nail holes are drilled, the drilled hole may collapse because hole surfacing soil is saturated or is filled with water. Therefore, a drilled hole cannot support itself and in result the hole will collapse. Furthermore, when the soil nails are being grouted, groundwater inside the drilled hole may affect the water/cement ratio of the cement grout. This may affect the grout quality and reduce the cement grout strain capabilities. 
3. Utilities: Soil nails are drilled inside the slope. Behind of slope may contain utilities such as buried water pipes, underground cables and drainage systems. There are some limitations that state that soil nails must have a safe distance between soil nails and these utilities. Therefore, a soil nail must change its inclination or length or spacing to achieve this distance.
4. Vibration sensitive structure: During the drilling procedure, vibration may occur and cannot be avoided. Some building structures are vibration sensitive such as Historical Buildings. Therefore, soil nailing is not the suitable method for slope improvement in these cases. 
5. Rock base slope: Some cut slope contain only few meters of top soil. During site investigation the deep layer soil type or a large boulder may be undetected (which would be possible with ground investigation, indicating it’s importance). When drilling the soil nail holes and the rock layer is reached, dust and stone powder may affect the environment and public health.

PLATE LOAD TEST

This is a field test for determining the ultimate bearing capacity of soil. The test consists of loading a steel plate placed at the foundation level and recording the settlements corresponding to each load increment. This test load is gradually increased till the plate starts to sink at a rapid rate. The total value of load on the plate in such a stage divided by the area of the steel plate gives the value of the ultimate bearing capacity of soil. The ultimate bearing capacity is divided by suitable factor of safety (which varies from 2 to 3) gives the value of safe bearing capacity of soil.

Figure 1. Vertical Section of Plate Load Test

Procedure of plate load test as follows: 

1. A pit is dug at site up to the depth at which the foundation is proposed to be laid. The width of the pit should be at least 5 times the width of the test plate. At the centre of the pit a small square depression or hole is made whose size is equal to the size of the test plate and bottom level of which corresponds to the level of actual foundation. The mild steel plate (also known as bearing plate) used in the test should not be less than 25 mm in thickness and its size may vary from 300 to 750 mm.

2. The load is applied to the test plate through a centrally placed column. The loading to the test plate is applied with the help of a hydraulic jack. The reaction of the hydraulic jack is borne either by the gravity loading platform or by the reaction truss method. Figure 1 shows gravity loading platform. In gravity loading method, a platform constructed over a vertical column resting on the platform. The loading is done with the help of sand bags, stones or concrete blocks. In the case of reaction truss method, the truss is usually made of mild steel sections, is held to the ground through soil anchors. The lateral stability of truss is achieved by the guy ropes.

3. The load is applied in convenient increments say of about one-fifth of the expected safe bearing capacity or one-tenth of the ultimate bearing capacity.

The settlement of plate is noted by means of dial gauges mounted on independent datum bar. The load is directly recorded from the pressure gauge of the hydraulic jacks. The observations are properly recorded and load settlement graph is plotted as shown in the figure 2. At the points where graph sharply takes turn is noted. The point gives the ultimate load intensity (bearing capacity).

Figure 2. Typical load settlement curve for different soils

The bearing capacity and the safe bearing capacity of the soil are calculated as:

Following are the limitations of the plate load test:

1. The test duration is short and hence does not give the ultimate settlement particularly in case of cohesive soils.

2. The test results reflect the character of soil located within the depth less than twice the width of bearing plate. It corresponds of a pressure bulb of one-tenth of the loading intensity at the test plate. The foundations of structures are generally larger and hence the settlement and resistance against the shear failure will depend on the properties of a much thicker stratum of the soil. 

3. For clayey soils, the ultimate pressure for a large foundation is nearly the same as that on the test plate. But for dense sandy soils, the bearing capacity increases with the size of the foundation and hence the results obtained on the small size bearing plates are found to give conservative values.

BOUSSINESQ’S SOLUTION OF VERTICAL STRESSES DUE TO A CONCENTRATED LOAD

In 1885, Boussinesq published equations to determine the state of stress in a subgrade material. He investigated the stresses in a semi-infinite, elastic, isotropic and homogenous solid medium, loaded manually on its upper plane surface by a concentrated point load. The material is also considered weightless and unstressed.

Figure 1. Stresses due to a concentrated load

Figure 1 shows a horizontal surface of the elastic continuum subjected to a point load Q at point O. the origin of the coordinates is taken at O. Using logarithmic stress function for the solution of elasticity problem, Boussinesq proved that the polar stress σ_R at point P(x,y,z) is given by-

Where,

R = polar distance between the origin O and point P.

β = angle which the line OP makes with the vertical.

Obviously,

Or,

 Where,

 And,

 And,

 The vertical stress at a point P is given by-

 Where,

The coefficient I_B is known as the Boussinesq influence coefficient for the vertical stress. The values of I_B can be determined for the given value of r/z from the above equation. The computed values are tabulated as shown in the table below.

Table 1. Values of Boussinesq's Coefficient (I_B)

The following points are worth noting when using the above equation:

1. The vertical stress does not depend upon the modulus of elasticity (E) and the Poisson’s ratio (ν). But the solution has been derived assuming that the soil is linearly elastic. The stress distribution will be the same in all linearly elastic materials.

2. The intensity of vertical stress just below the load point is given by-

3. At the surface (z = 0), the vertical stress just below the load is theoretically infinite. However, in an actual case, the soil under the load yields due to a very high stresses. The load point spreads over a small but finite area, and therefore, only finite stresses develop.

4. The vertical stress (σ_z) decreases rapidly with an increase in r/z ratio. Theoretically, the vertical stress would be zero only at an infinite distance from the load point.

5. Boussinesq solution can even be used for negative (upward) loads. For example, if the vertical stress decreases due to an excavation is required, the negative load is equal to the weight of the soil removed. However, as the soil is not fully elastic, the stresses determined are necessarily approximate.

6. The field measurements indicate that the actual stresses are generally smaller than the theoretical values given by Boussinesq’s solution at shallow depths. Thus, the Boussinesq solution gives conservative values and is commonly used in soil engineering problems.

Limitations of Boussinesq’s Solution:

1. The solution was initially obtained for determination of stresses in elastic solids. Its application to solids may be questioned, as the solids are far from purely elastic solids.

2. The application of Boussinesq’s solution can be justified when the stresses changes are such that only a stress increase occurs in the soil. The real requirement for use of the solution is not that the soil be elastic (i.e. fully recoverable), but it should have a constant ratio between stress and strain. When the stress decrease occurs, the relation between stress and strain is not linear and, therefore, the solution is not strictly applicable. If the stresses included in the soil are small in comparison with the shear strength of the soil, the soil behaves somewhat elastically and the Boussinesq solution can be used.

3. For practical cases, the Boussinesq solution can be safely used for homogenous deposits of clay, man-made fills and for limited thickness of uniform sand deposits. In deep sand deposits, the modulus of elasticity increases with an increase in depth and, therefore, the Boussinesq solution will not give satisfactory results. In this case, the assumption of proportionality between stress and strain cannot be justified. For such a case, non-linear elastic solutions or elastic-plastic solutions are required.

4. The point load applied below ground surface cause somewhat smaller stresses than are caused by surface loads, and therefore, the Boussinesq solution is not strictly applicable. However, the solution is frequently used for shallow footings, in which z is measured below the base of the footing.

BASEMENT EXCAVATION

The various methods of basement excavation are as follows:

Perimeter Trench Method: The perimeter trench method is used where weak soils are encountered; a trench wide enough to enable the retaining walls to be constructed is excavated around the perimeter of the site, and timbered according to the soil conditions. The permanent retaining walls are constructed within the trench excavation and the timbering is removed; the dumpling or middle can then be excavated and the base cast and joined to the retaining walls. This method could also be used in firm soils when the mechanical excavators required for bulk excavation are not available.

Figure 1. Perimeter Trench Method

Ground Anchorage Method: Ground anchor is basically a pre-stressing tendon embedded and anchored into soil or rock to provide resistance to structural movements by a “tying back" principle. 

Ground anchor can be classified into: 

1. Rock anchor – for anchorage in rock 

2. Injection anchor – suitable for most cohesive and non-cohesive soils 

Figure 2. Method to form Ground Anchor

Method to form a ground anchor: A hole is predrilled on soil or rock in position carefully calculated. For rock anchor, an anchor bar with expanded sleeves at the end is inserted into the hole. A dense high strength grout is injected over a required length to develop sufficient resistance to hold the bar when it is stressed. Stressing is by hydraulic mean and when the stress is developed, the head of the bar is hold by an end plate and nut.

For injection anchor, a hole should be bored usually with an expanded end to increase anchorage ability. The pre-stressing bar is placed into the bore hole and pressure grouted over the anchorage length. Gravel placement ground anchor can also be used in clay soils for lighter loading. In this method irregular gravel is injected into the borehole over the anchorage length to form an end plug. The gravel plug is then force into soil using percussion method through casing, forming an enlarged end. A stressing bar is inserted into the casing and pressure grouted over the anchorage length as the casing is removed.

Reinforced Concrete Bored Piles: There are two main types of RC bored pile retaining wall:

i. Contiguous bored pile retaining wall

ii. Secant bored pile retaining wall 

Figure 3. Contiguous Bored Pile Wall

Contiguous bored pile retaining wall: A contiguous bored pile is formed by constructing a series of individual vertical RC piles. The diameter of each pile in a contiguous piled wall is usually not less than 300 mm diameter. A small space usually of 100 mm is left in between adjacent piles. Once all the piles have been constructed the top of the piles are usually joined together by an RC capping beam. Contiguous piling is used in case of self-supporting soils such as stiff clays.

Figure 4. Contiguous Bored Piled Wall with RC Capping Beam

Figure 5. Basement Construction using Contiguous Bored Pile Wall

Secant bored pile retaining wall: Secant bored pile walls are made using two types of piles: a soft unreinforced pile and a hard, strong reinforced concrete pile. The minimum diameter of each pile in a secant pile wall is usually 450 mm. 

Figure 6. Secant Bored Pile Wall

The construction sequence is:

(a) A line of unreinforced piles is constructed using low strength concrete. These are the soft piles.

(b) Then a second line of piles is constructed between and overlapping with the soft piles. The second line of piles is reinforced and uses high strength structural grade concrete. These are the hard piles.

The hard piles provide the structural strength. The soft piles act to fill the gap between the hard piles and hold back any ground or water that would otherwise be able to flow between the hard piles. Secant piling is used where the ground has a perceived risk of becoming fluid, commonly due to the combination of non-cohesive deposits and water. This technique will reduce the ground water ingress if designed and constructed correctly.

Figure 7. Steel Sheet Pile Wall

Steel Sheet Piles: Sheet piled retaining walls are made by using interlocking steel piles. The steel sheet piles are generally driven or jacked into the ground using specialist plant. The plant is usually comparatively large which can be a limiting factor on their use. In addition head height clearance of at least the length of the sheet pile is required to allow installation. As a result steel sheet piles usually cannot be used underneath buildings. They are generally more suitable for open sites with good access as in the case of swimming pool.

Sheet piles are usually installed by either:

Percussive methods: hammering the sheet piles into the ground. This is generally not acceptable in urban areas due to excessive noise created by hammering.

Jacking: forcing the sheet piles into the ground using heavy hydraulic drivers.

QUICKSAND

The shear strength of a cohesionless soil depends upon the effective stress. The shear strength is given by:

Where = effective stress
φ = angle of shearing resistance

Let us consider a soil specimen of length L subjected to an upward pressure shown in figure 1. Let us consider the stresses developed at section C – C.

Figure 1. Quicksand Condition

When water flows in an upward direction through soil, the effective pressure is given by:

where ps = seepage pressure

If the seepage pressure becomes equal to the submerged weight of the soil, the effective pressure of the soil reduces to zero. In such a case, a cohesionless soil loses all its shearing strength and the soil cannot support any load. In other words, the soil particles ted to be lifted up along with the flowing water. The soil is said to have become ‘quick’ or ‘alive’ and boiling will occur. The popular name of this phenomenon is quicksand. It may be emphasized that quicksand is not a type of sand but only a hydraulic condition occurring within a cohesionless soil when its effective pressure is reduced to zero due to upward seepage force. Thus during the quicksand condition:

The hydraulic gradient ic at which the quick condition occurs is called the critical hydraulic gradient. For loose deposits of sand or silt, if void ratio e is taken as 0.67 and G as 2.67, the critical hydraulic gradient works out to be unity.

Seepage forces affect sands more than clays because sands do not possess cohesion, while fine sands and silts have some inherent cohesion which holds the soil grains together even at the critical hydraulic gradient. In sands, the shear strength s is given by:

Hence, when

In clays, however,

The cohesion component of shear strength is independent of . Boiling does not occur in coarse sands and gravels either, because these soils are highly pervious; hence, according to Darcy’s law, large discharges are required to produce a critical gradient of unity and such flows rarely materialize in practice.

When a natural soil deposit becomes quick, it cannot support the weight of a man or an animal. But contrary to common belief, the soil does not suck the victims beneath its surface. As a matter of fact, quick sand behaves like a liquid with a unit weight about twice that of water. A person can easily float in it with about one-third of his body out of quick sand. However, quick sand is highly viscous and movement in it would require a great effort and energy. A person may die by suffocation if he gets tired and let his head fall into the quick sand in panic.

If a person is caught in quick sand conditions, he should keep his head high above the soil surface and move slowly towards the bank. He should try to catch some tree on the bank and try to pull himself out of the quick sand.